Irrigation sprinklers are vital components to an irrigation system, spraying a stream of water over a desired area to irrigate lawns, gardens, or other terrain. While many irrigation sprinklers act in a superficially similar manner to distributing water from their nozzles, the internal designs of these sprinklers may vary widely in design.
One popular irrigation sprinkler design is the gear driven rotary sprinkler. This sprinkler design rotates to dispel water in various directions and is driven in rotation by the force of water passing by an internal turbine. The turbine drives a series of planetary gear stages, used for reducing the speed of the sprinkler rotation relative to the turbine. Further, additional mechanisms may be included for rotational reversing capabilities. Examples of different designs may be seen in U.S. Pat. Nos. 4,625,914; 5,330,103; and 5,662,545; all hereby incorporated by reference.
Previous adjustable arc rotary sprinkler designs allow a user to water varying areas in one mode only, namely a reversing circle mode, streaming water back and forth within a horizontal arc. Hence, in order to water a complete circle around the sprinkler, the user must set the arc watering limits to 360 degrees. At this setting the prior art sprinkler rotates in one direction until it hits an arc stop, then reverses direction until it hits the other arc stop.
This strategy for full circle watering in prior art models provides uneven water distribution because the sprinkler stops for an instant when reversing direction. Since the point of rotation reversal (i.e., the arc stop position) is approximately the same in each direction when watering a 360 degree arc, that reversal point receives significantly more water over time than the other points on the arc. Consequently, the watering pattern for the 360 degree, reverse direction type of sprinkler can lead to uneven grass growth or even damage to the lawn or vegetation.
What is desired is an adjustable arc rotary sprinkler that evenly distributes water when watering a full circle around the sprinkler.